1. Field of the Invention
The present invention relates to a digital television, and more particularly to, an apparatus and method for format converting a video and outputting the video in a different format.
2. Description of the Related Art
According to the introduction of digital TVs and various display apparatuses, more various kinds of images become inputs and outputs in comparison with the existing analogue TVs. In order to convert input images of various sizes into output images of different sizes, a format conversion apparatus is essentially utilized.
Also, the needs to output videos of various formats to the existing NTSC screens have been increased. When converting a high-resolution video format to an NTSC video size by using a general format conversion apparatus, unnecessary memories become wasted.
FIG. 1 shows an example of the related art apparatus for format converting a video.
That is, an input video is stored in a line memory part 101 including a plurality of line memories and is input to a vertical filter 102. The vertical filter 102 limits a bandwidth of the input video for preventing aliasing when reducing the input video in the vertical direction.
A vertical format converting part 103 performs a format conversion in the vertical direction of the video data, which is filtered in the vertical direction in the vertical filter 102, into proper output sizes. A horizontal filter 104 receives an output from the vertical format converting part 103. The horizontal filter 104 also prevents the aliasing possibly generated in an output video by limiting a bandwidth of the input video. The video data, which is filtered in the horizontal direction, is format converted in the horizontal direction by a horizontal format converting part 105.
However, the related art apparatus for format converting a video has a disadvantage that the waste of the memory is relatively large since a large number of line memories are required for the high-resolution video. That is, the size of each line memory is increased since the size of each line memory is determined by the size of the input video, which was not format converted yet.
In order to resolve this disadvantage, a buffer may be utilized. However, it still has a problem that the memory bandwidth is increased if a vertical filter having a plurality of taps is used in order to obtain a good quality of the NTSC screen.
Accordingly, the present invention is directed to an apparatus and method for format converting a video that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide an apparatus and method for format converting a video in which the size of a line memory is reduced by format converting the input video data in a horizontal direction, storing the video data in the line memory, and format converting the video data stored in the line memory in a vertical direction.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the scheme particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, an apparatus for format converting a video according to an embodiment of the present invention includes: a horizontal format converting unit for format converting input video data in a horizontal direction suitable for horizontal output size; a line memory unit for storing the horizontally format converted video data for format conversion in a vertical direction; and a vertical format converting unit for format converting the video data output from the line memory unit in a vertical direction suitable for vertical output size.
The apparatus for format converting a video according to an embodiment of the present invention further includes an area division controller for receiving information on the number of lines of the video data required for the vertical format conversion in a next horizontal synchronization period from the vertical format converting unit, wherein the horizontal format converting unit temporally divides the video data in the horizontal direction in accordance with an area division control signal of the area division controller.
The horizontal format converting unit temporally divides the video data equivalent to the number of the lines provided from the vertical format converting unit in accordance with the area division control signal of the area division controller and sequentially format converts the temporally divided video data in a next horizontal synchronization period in turn.
The horizontal format converting unit temporally divides the respective lines equivalent to the number of the lines of the video data under the control of the area division controller.
The horizontal format converting unit temporally divides the respective lines in such a manner that each area of the respective lines partially overlaps a next area.
The apparatus for format converting a video according to an embodiment of the present invention further includes horizontal and vertical filters respectively at front ends of the horizontal format converting unit and the vertical format converting unit, for limiting band widths of the video data.
The line memory unit includes a plurality of line memories, and the number of the line memories is determined by the number of taps of the vertical filter at a rear end.
The apparatus for format converting a video according to an embodiment of the present invention further includes a data divider for sequentially dividing data stored in the line memories and outputting the divided data to the vertical filter.
In another aspect, an apparatus for format converting a video of the present invention includes: a vertical format converting unit for format converting the horizontally format converted video data in a vertical direction suitable for vertical output size and providing information on the number of lines of input video data required for the vertical format conversion in a next horizontal synchronization period; an area division controller for generating an area division control signal for temporally dividing the respective lines in a horizontal direction based on the information on the number of lines; a horizontal format converting unit for temporally dividing and format converting the input video data in accordance with the area division control signal of the area division controller; and a line memory unit for storing the horizontally format converted video data and outputting the stored data to the vertical format converting unit for the vertical format conversion.
The apparatus for format converting a video according to an embodiment of the present invention further includes horizontal and vertical filters respectively at front ends of the horizontal format converting unit and the vertical format converting unit, for limiting band widths of the video data.
The apparatus for format converting a video according to an embodiment of the present invention further includes a data divider for sequentially dividing data stored in the line memories and outputting the divided data to the vertical filter.
In other aspect, a method for format converting a video of the present invention includes the steps of: format converting the horizontally format converted video data in a vertical direction suitable for vertical output size and providing information on the number of lines of input video required for the vertical format conversion in a next horizontal synchronization period; generating an area division control signal for temporally dividing the respective lines in a horizontal direction based on the information on the number of lines; temporally dividing and format converting the input video data in accordance with the area division control signal of the area division controller; and storing the horizontally format converted video data and outputting the stored data to the vertical format converting step for the vertical format conversion.
The method for format converting a video according to an embodiment of the present invention further includes the steps of horizontally and vertically filtering the input video data respectively at front ends of the horizontal format converting step and the vertical format converting step to limit bandwidths of the input video data.
The horizontal format converting step includes the step of temporally dividing respective lines of the input video data equivalent to the number of the lines provided from the vertical format converting step in accordance with the area division control signal.
According to the present invention, an input video is format converted in a horizontal direction according to a horizontal output size to store in a line memory and the image stored in the line memory is format converted in a vertical direction according to a vertical output size, such that the amount of line memory required for video processing and bandwidths required for outputting various sizes of input videos including the high resolution video format used in the digital TVs by reducing into the NTSC or standard screen quality video format are minimized.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.